大乘起信論別記 1.109

1.109

言「眾生依心」者，諸生滅法，聚集而生，故名眾生。而無自體，唯依心體故，言依心。能依眾生只是意、意識故，言「意、意識轉」。此即表二章門。

As for "sentient beings rely on the mind": the various dharmas of arising and ceasing gather together and arise, hence they are called "sentient beings" (sattva/produced beings). Having no independent substance of their own, they rely solely on the mind-essence; hence it says "relying on the mind." The sentient beings that rely upon it are merely manas and manovijñāna; hence it says "manas and manovijñāna evolve." This indicates the two chapter headings.